>> As for a compression leak: there is only two reason for this. One
>> is a crack in the head. Make sure the machine shop is using the
>> special chemicals required to find cracks in AL heads. I honestly
>> don't think this is the problem as, somewhere I had seen that
>> small cracks are exceptable for rebuilds.....go figure???
>
>Not on my rebuilds!  If anyone told you this run, don't walk, to another
>mechanic.  This is totally unacceptable, but people will do it to get an
>engine running well enough to sell the vehicle.

As to cracks, first in aluminum, nothing special, any standard dye
penetrant set will find them fine, back at the rocket factory we used
same run of the mill stuff on steel welds or $15000 machined beta-c
titanium parts and anything in between.  If you'd like to do it yourself
pick up one of those sets from eastwood ($$$) or just buy the the dye
and "developer" (white chalky stuff in a spray can) from a local place
or McMaster-Carr.  Dye pen will find 99% of anything of consequence
you need to worry about.  Remeber though you got to have the part
clean and although for me that means the bead blast cabinet, strictly
speaking bead blasting can smear metal over cracks so you can't see
it.  Still a lot of people do since the EPA took away the cold tanks.
The pressure wash cabinets do a fair job, not beautiful.

Secondly, on Vanagon wasserboxer heads, I've never, EVER, seen a
2.1 head with more than 50k on it not cracked with a teeny minor little
crack between the seats, the one Bentley refers to.  These are utterly
trivial.  A number of the big name rebuilders out there send heads out
without doing anything to these, and frankly after the quality of welding
I saw on the last waterboxer head I bought with a replaced seat, I'd
personally just as soon trust one VW installed with an almost infintesimal
crack to what people are doing themselves.  VW waterboxers also crack
the water jacket to the outside, got to watch that though.  Unlike with
air cooled, I'd be inclined to use a good used waterboxer core with a trivial
crack any day, or go for the redesigned AMC head.  For T4 air cooled though,
just say it, never again a rebuilt head, not by anyone, go for Riechert's new
German cores.  For my money a waterboxer head has proven itself easily
good for 150-200k or more with just a valve job assuming the gasket surface
corrosion didn't get to it.  If a mechanic shows you a barely visible crack
between the seats, don't get in a sweat, but always run an internal cost
comparison to what you are putting into having a head rebuilt versus what
the new head is going to cost.  Unless you just intend to bead blast, JB
Weld the gasket surface, touch up the seats and maybe replace the exhausts,
you are going to get into more money than the thing is worth, surely more
than a rebuilt set will cost you from one of the big name suppliers.  Course
if you take the prior approach yourself, you'd probably still get the
75-100k or
so out of the heads that the new set is going to get you before dripping.
So do what you will, YMMV.

John
jander14@wvu.edu